SLLSFW6B March 2024 – July 2026 ISOUSB211-Q1
PRODUCTION DATA
In the application example shown in Figure 8-6, ISOUSB211-Q1 is powered using USB VBUS on the connector side, and a local 3.3V digital supply on the microcontroller side to generate V3P3Vx. An external LDO or DC-DC buck converter is used to generate V1P8Vx on both sides.
In this scenario, the total power consumption from both sides taken together is:
VBUS1 × IVBUS1 + V1P8V1 × I1P8V1 + V3P3V2 × I3P3V2 + V1P8V2 × I1P8V2
Assuming 5.25V as the maximum value of VBUS, and 1.89V as the maximum value of the external 1.8V power supply, the internal power dissipation is calculated as
5.25V × 13.5mA + 1.89V × 96mA + 3.5V × 13.5mA + 1.89V × 96mA = 481mW.
Since the junction-to-air thermal resistance is 44.2°C/W, this power dissipation results in a 22°C internal temperature rise. Ambient temperature up to 128°C can be supported for this configuration.
TLV741P and TLV62568 are examples of low-cost LDO and buck converters, respectively, that can be used in this application. Both options reduce the power dissipation in ISOUSB211-Q1. However, the buck converter additionally reduces power dissipation at the system level, and the current drawn from VBUS and local 3.3V supplies.
This configuration offers the lowest power dissipation and the highest ambient temperature operation using external regulators.